QuoteBenjamin MoodyFurthermore, the spec doesn't say in which direction the arctangents are computed (i.e., does the image appear in its natural orientation as viewed from the outside of the cylinder, or from the inside?)

I assumed, as the result of the LDraw orientation of up=-y, textures should use top/left orientation for uv at the level texmap is at.

QuoteBenjamin MoodyThe spec is even less clear about spherical textures, as it doesn't say whether the third control point corresponds to the "left" or the "right" side of the texture. In my implementation I've been (somewhat arbitrarily) assuming that it goes on the right.

I too used right, thinking the p1,p2,p3 triangle is to be used CCW when calculating the sphere up vector.

LDraw.org Forums are hosted by P-Sky Software powered by Phorum.LDraw.org Forum template designed by Scriptmonkeys, modified by LDraw.orgLEGO® is a registered trademark of the LEGO Group, which does not sponsor, endorse, or authorize this site.
Visit the official Lego website at http://www.lego.com.LDraw is a completely unofficial, community run free CAD system which represents official parts produced by the LEGO company.